President Donald Trump said Friday that Iran's leaders have not yet agreed to a deal to end the war with the United States because "they're strong" and "they're proud," but predicted Tehran will ultimately come to terms because "they've got no choice."

Trump made the remarks to NBC News' "Meet the Press" moderator Kristen Welker during a sit-down in Chippewa Falls, Wisconsin, as the conflict, now in its fourth month, continues to test a fragile ceasefire and stalled negotiations.

The president, pushing back on critics urging a faster resolution, told Welker the talks would take time.

"These people have been fighting for 47 years. They've been killing Americans," Trump said of Iranian leaders, adding that he was "into three months" of a war he likened to Vietnam, which he described as having lasted 19 years.

He said Democratic critics would not press him on the timeline if his party was reversed.

Trump asserted the U.S. and Israeli campaign, which began with strikes on Iran on Feb. 28, has "totally destroyed" Iran's military, though he acknowledged Tehran retains some capability.

"I would say percentage-wise, maybe 21%-22% of their missiles," Trump said. "It's a lot of missiles, but it's not what it was when we first attacked."

That residual arsenal was on display this week.

Iranian drones struck Kuwait International Airport on June 3, killing one person, wounding dozens and briefly closing the country's main aviation hub, the latest blow to a ceasefire first reached in April and extended several times since.

Secretary of State Marco Rubio told House lawmakers Wednesday that the offensive U.S. operation, code-named Epic Fury, "has concluded," and that subsequent American strikes near the Strait of Hormuz were "defensive in nature," carried out in response to Iranian attacks on shipping.

Iran's closure of the strait, a chokepoint for global oil traffic, has driven up crude prices and pushed U.S. gasoline costs higher, sharpening political pressure on Trump and congressional Republicans.

Trump signaled this week that he is prepared to walk away if Tehran balks.

In a Wednesday interview with the New York Post's "Pod Force One" podcast, he called it "unlikely" the U.S. blockade of Iranian ports, imposed after Tehran shut the strait, would still be in force by Labor Day, and floated an alternative to a negotiated settlement: "Do we sign a deal or we do it the other way? And the other way is not nice."